There has conventionally and generally been known a technique whereby to control the vehicle speed of a vehicle set by a driver or the like to a fixed target vehicle speed or to control the vehicle speed of a vehicle so as to maintain the vehicle-to-vehicle distance between an own vehicle and a preceding vehicle at a set target vehicle-to-vehicle distance.
Further, as described in, for example, Patent Document 1, there has conventionally been known a technique in which the vehicle speed of a vehicle is controlled to attain a target acceleration/deceleration speed requested by a driver in a travel environment determined to be safe, while the target acceleration/deceleration speed is forcibly changed to give a higher priority to safety in a travel environment determined to be dangerous.